According to the National University of Singapore (NUS), only 40 per cent of waste tyres are recycled – the rest are either burned to generate electricity or thrown into landfills. But now scientists at the university have developed a way to convert old tire rubber into high-value aerogels.
The team, led by Associate Professor Duong Hai-Minh of the National University of Singapore and Professor Nhan Phan-Thien, first cut discarded car tyres into fine rubber fibers. The fibers are then immersed in a solution consisting of water and a small amount of “eco-friendly” solvents, which interlink the fibers. The mixture is mechanically stirred for 20 minutes to form a gel in which the connected fibers are suspended evenly. The gel is then poured into the mold and dried freeze-dryfort for 12 hours at a temperature of -50oC (-58oF).
The solid rubber aerogels are said to be lightweight, highly absorbent (can be used to absorb oil leaks) and provide excellent insulation and sound insulation. In addition, unlike traditional fragile aerogels, they are considered to be highly durable. If a chemical called methylene-based trimethylsian is coated, it can also be water resistant.
“The manufacturing process is simple, cost-effective and environmentally friendly,” says Hai-Minh. The entire production process takes 12 to 13 hours to complete, and the cost of producing a rubber aerogel measuring 1 square meter and 1 cm thick is less than S$10. The process can also be easily scaled up for mass production, making rubber aerogels a commercially attractive product. “
Scientists recently published a paper on the study in the journal Colloids and Surfaces A: Physicochemical and Engineering Aspects.